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Commit 034b91a3 authored by Latchesar Ionkov's avatar Latchesar Ionkov Committed by Linus Torvalds
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[PATCH] v9fs: fix corner cases when flushing request 



When v9fs_mux_rpc sends a 9P message, it may be put in the queue of unsent
request.  If the user process receives a signal, v9fs_mux_rpc sets the
request error to ERREQFLUSH and assigns NULL to request's send message.  If
the message was still in the unsent queue, v9fs_write_work would produce an
oops while processing it.

The patch makes sure that requests that are being flushed are moved to the
pending requests queue safely.

If a request is being flushed, don't remove it from the list of pending
requests even if it receives a reply before the flush is acknoledged.  The
request will be removed during from the Rflush handler (v9fs_mux_flush_cb).

Signed-off-by: default avatarLatchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@ericvh.myip.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 05818a00

fs/9p/mux.c

+11 −4
Original line number Diff line number Diff line
@@ -471,10 +471,13 @@ static void v9fs_write_work(void *a) 
		}



		spin_lock(&m->lock);

		req =

		    list_entry(m->unsent_req_list.next, struct v9fs_req,

again:

		req = list_entry(m->unsent_req_list.next, struct v9fs_req,

			       req_list);

		list_move_tail(&req->req_list, &m->req_list);

		if (req->err == ERREQFLUSH)

			goto again;



		m->wbuf = req->tcall->sdata;

		m->wsize = req->tcall->size;

		m->wpos = 0;
@@ -525,7 +528,7 @@ static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req) 
	struct v9fs_str *ename;



	tag = req->tag;

	if (req->rcall->id == RERROR && !req->err) {

	if (!req->err && req->rcall->id == RERROR) {

		ecode = req->rcall->params.rerror.errno;

		ename = &req->rcall->params.rerror.error;
@@ -551,7 +554,10 @@ static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req) 
			req->err = -EIO;

	}



	if (req->cb && req->err != ERREQFLUSH) {

	if (req->err == ERREQFLUSH)

		return;



	if (req->cb) {

		dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",

			req->tcall, req->rcall);
@@ -812,6 +818,7 @@ v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err) 
	struct v9fs_mux_rpc *r;



	if (err == ERREQFLUSH) {

		kfree(rc);

		dprintk(DEBUG_MUX, "err req flush\n");

		return;

	}